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Workshop Manual
Chain Saws
Contents
This manual covers models:
2036/2040
2041/2045/2050
2054/2055
625/630/670
2077/2083
2095
General recommendations 2
1. Safety equipment 3
2. Starter unit 17
3. Electrical system 23
4. Fuel system 35
5. Centrifugal clutch 55
6. Lubrication system 65
7. Cylinder and piston 77
8. Crankshaft and crankcase 93
9. Tools 115
10. Technical data 127
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502 51 02-01
General recommendations
Keep this in mind:
Do not start the engine without the clutch and clutch drum fitted.
Do not touch hot parts such as the silencer and clutch before
they have cooled sufficiently to avoid burn injuries.
Avoid getting petrol on bare skin or in the mouth.
Wipe up spilled oil immediately from the floor to avoid slipping
and subsequent injury.
Do not use tools which are worn or fit badly, e.g. nuts and
screws.
Never start the engine indoors. Exhaust fumes are toxic!
+ Always work on a tidy work bench.
+ Always work methodically to be sure that all parts are correctly
assembled and that screws and nuts are tightened.
+ Use protective cream on your hands. It reduces the risk of
infection and enables dirt to be more easily washed off.
Prolonged contact with motor oil can be hazardous to health.
+ Use special tools when so recommended in order to workcorrectly.
Fire hazard
Handle petrol with respect since it is highly inflammable.
Do not smoke and make sure that there are no naked flames or
sparks in the vicinity.
Make sure that there is a functioning fire extinguisher in the vicinity.
Do not attempt to extinguish a petrol fire with water.
Toxic fumes
Read the instructions carefully when using cleaning liquids.
Make sure that there is adequate ventilat ion when handling petrol,
trichloroethylene and other viscous liquids.
The engine exhaust fumes are toxic. Test run the engine only whenthere is good ventilation, preferably outdoors.
Special tools
Some work operations in this workshop manual require the use
of special tools. In each section where this is appropr iate the tool
and order number are illustrated.
We recommend the use of special tools partly to avoid personalinjury and partly to eliminate expensive damage to the
components in question.
Sealing surfaces and gaskets
Make sure that all sealing surfaces are clean and free from the
residue of old gaskets. Use a tool which will not damage the
sealing surface when cleaning it. Scratches and irregularities
are removed with a fine, float cut file.
Sealing rings
Always replace a sealing ring which has been dismantled. The
sensitive sealing lip can easily be damaged and result in poor
sealing capacity. The surface which the seal seals must also becompletely undamaged. Lubricate the sealing lip with grease
before it is fitted and make sure that it is not damaged, e.g. by
shoulder and splines on a shaft. Use tape or conical sleeve as
protection. It is important that the sealing ring is correctly turned
for it to function as intended.
The engine exhaust from this productcontains chemicals known to the State
of California to cause cancer, birthdefects or other reproductive harm.
WARNING!
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Safety equipment
1
1.
Contents
Dismantling 4
Disassembly 4
Fitting 6
Dismantling, mod. 2054/2055 7
Fitting, mod. 2054/2055 9
Dismantling, mod. 2077/2083 10
Fitting, mod. 2077/2083 11
Checking of automatic function 12
Checking of brake action 13
Chain catcher 13
Throttle lock 13
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Safety equipment1
!
505 38 17-05
!
In addition to the chain brake the chain catcher andright-hand guard on the rear handle are also con-sidered part of the chain saws safety equipment.
It is obviously important that the chain brake
functions as intended, but it is also important thatthe chain catcher is undamaged and in position. In
the event of a chain break this will catch up thechain so that the hand will not be injured.
WARNING!
Protective goggles must beworn during all work on the
chain brake to prevent perso-nal injury if for some reason the
brake spring should fly off.
Dismantling
Dismantle the chain brake from the chain
saw.
Disassembly
Release the chain brake.
Press out the one half of the hand guards
bearing.
Press out the other half of the hand guardsbearing.
Dismantling
Remove the guide bar's attachment nuts
and lift off the clutch cover with the chain
brake.
Clean from sawdust and dirt.
WARNING!
The brake spring is tensioned with a
very large force and can cause per-
sonal injury if the brake is not
released prior to further work.
Disassembly
Release the chain brake.
Unscrew the screw to the hand guards
bearing completely, and then screw inapprox. 2 turns.
Drive out the bearing by tapping the screw
with a hammer.
Press out the other half of the bearing bymeans of suitable mandrel, e.g.
505 38 17-05.
Lift off the hand guard.
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Safety equipment 1
!
Remove the screws and the cover overthe brake spring.
Bend up the brake spring.
Press out the toggle-joints bearing pin
and lift off the complete brake mechanism.
Press out the plate spring with a suitablemandrel.
Remove the screws and lift off the cover
over the brake spring.
WARNING!
The brake spring is tensioned and
can slip out of its position.
Use a screwdriver and carefully bend upthe spring.
Press out the toggle-joints bearing pin by
means of a suitable mandrel.
Lift off the complete brake mechanism.
Press out the plate spring with a suitablemandrel, and replace if necessary.
Clench the spring eye with a pair of pliers
so that it is easier to fit the new spring.
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Safety equipment1
0,8 mm
The brake band must have a minimum
thickness of 0.8 mm at the most wornpoint.
Remove the screw and replace the brake
band.
Dismantle the lock-ring and the pin in
order to replace the spring inside thehand guard.
Assembly
Grease the spring and fit it in the handguard.
Check the wear on the brake band.
At the most worn point the band must
have a thickness of at least 0.8 mm.
Otherwise it should be replaced with a
new band.
Remove the screw and fit a new brake
band.
Check after fitting that the brake band
does not touch the toggle-joint and ob-
struct its movement.
Inside the hand guard there is a spring
which is accessible for replacement afterthe lock-ring and pin are dismantled.
Use a small screwdriver to remove thelock-ring.
Assembly
Grease the spring and push it in the handguard as far as it goes.
Fit the pin and lock-washer.
NOTE!
The pin should not go through the eye on
the spring.
Check that the spring is turned correctly.
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Safety equipment 1
!
A
B
Fit the brake mechanism in the clutch
cover.
Lubricate the bearing points with thin oil.
Press down the brake spring by means ofa Phillips screwdriver.
Fit the cover.
Grease the bearing surfaces and fit the
hand guard.
Check that the brake functions.
Dismantling
Mod. 2054/2055Remove the screw, sleeve and washer
for the hand guards bearing on the star-
ter unit side, including the clutch cover,
guide bar and chain.
Clean!
Place the brake mechanism in position
on the clutch cover.
Press in the toggle-joints bearing pin (A)
and place the tubular pin (B) in position.
Lubricate the bearing points with thin oil.
Press down the brake spring in the clutch
cover by means of a Phillips screwdriver.
WARNING!
Observe care to avoid injury if the
screwdriver slips.
Fit the cover over the spring mechanism.
Grease the bearing points for the hand
guard.
Press down the hand guard over the
bearing and fit both bearing sleeves.
NOTE!
Check that the bearing sleeves are placed
on the correct side.
Tension and release the chain brake a
number of times to check that it functions.
Dismantling
Mod. 2054/2055On these models the chain brakes hand
guard has an extra bearing point on the
starter unit side.
Remove the screw, sleeve and washerfor this bearing.
Remove the clutch cover, guide bar and
chain.
Clean from sawdust and dirt.
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Safety equipment1
Dismantle the protective plate over the
guide bar attachment and the chain brake.
Release the chain brake!
Remove the plate clamp over the brake
spring and bend away the spring.
Remove the lock-ring round the hand
guards bearing pin and lift off the brakemechanism.
Replace the plate insert in the hand guardif the pins are worn by first pressing out
the fitted pin.
Remove the protective plate over the
guide bar attachment.
Remove the screws and lift off the chain
brake.
Release the chain brake!
! WARNING!
The brake spring is tensioned with a
very large force and can cause per-
sonal injury if the brake is not released
prior to further work.
Remove the screw and plate clamp overthe brake spring.
Carefully bend away the spring by means
of a screwdriver.
NOTE!The spring has a certain tension even
when the brake is released, and thereforeit should be dismantled carefully.
Remove the lock-ring round the hand
guards bearing pin and lift off the brakemechanism.
If the pins on the plate insert in the handguard are worn the complete insert can
easily be replaced.
Press out the fitted pin with a suitable
mandrel and replace the insert.
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Safety equipment 1
0,8 mm
Dismantle the brake mechanism and
replace worn or damaged parts.
Fit the brake spring and plate clamp over
the spring.
Fit the chain brake on the crankcase.
Screw tight the cover plate over the guidebar attachment and fit the brakes bearing
on the starter unit side.
Dissassemble the brake mechanism and
replace worn or damaged parts.
The brake band should have a minimum
thickness of 0.8 mm at the most worn
place.
AssemblyMod. 2054/2055
Fit the brake in the reverse order to dis-
mantling.
Begin with by fitting the hand guard.
Lubricate all moving parts with thin oil.
Fit the brake spring by means of a Phillips
screwdriver.
WARNING!Observe care to avoid injury if the
screwdriver slips.
!
Fit the plate clamp over the spring.
Fit the chain brake on the crankcase.
NOTE!
Make sure that the guide pin on the brake
fits into the hole in the crankcase before
the screws are tightened.
Fit the cover plate on the guide bar attach-
ment.
Screw tight the screw for the brakes
bearing on the starter unit side.
Do not forget the washer between the
crankcase and brake!
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Safety equipment1
!
DismantlingMod. 2077/2083
Dismantle the chain brakes bearing on
the starter unit side.
Remove the clutch cover, guide bar and
chain.
Clean!Remove the screws and lift off the chain
brake.
Release the chain brake!
Lift up the toggle-joint carefully by means
of a screwdriver.
Dismantle the hand guard.
Press the hand guard out of the bearing.
DismantlingMod. 2077/2083
Remove the screw, sleeve and washer
for the chain brakes bearing on the star-
ter unit side.
Remove the clutch cover, guide bar andchain.
Clean from sawdust and dirt.
Remove the screws and lift off the chainbrake.
Release the chain brake!
!
NOTE!
The other end of the spring is controlled
by a pin which goes into the centre.
For this reason do not try to lift up thespring there.
Dismantle the hand guard.
Remove the lock-ring by means of a small
screwdriver.
Hold your thumb over so that the ringdoes not fly away.
Press out the hand guard from the bearing.
WARNING!
Observe care so that the sprin loaded
catch does not fly away.
WARNING!
The brake spring is tensioned with a
very large force and can cause perso-nal injury if the brake is not released
prior to further work.
Lift up the toggle-joint carefully by
means of a screwdriver.
Hold your hand over.
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Safety equipment 1
0,8 mm
Replace the hand guards bearing pin if it
is worn.
Press out the sprung tubular pin and pull
out the plate insert from the hand guard.
Clean and check all parts.
The thickness of the brake band should
be at least 0.8 mm.
AssemblyMod. 2077/2083
Fit the brake in the reverse order to dis-
mantling.
Press down the hand guard in the correctposition.
The hand guards bearing pin can now
easily be replaced.
Press out the spring tensioned tubular
pin and pull out the complete plate insert
from the hand guard.
Replace the insert if the bearing pin is
worn.
Clean all the parts of the chain brake and
check them for wear or damage.
The brake band should have a minimum
thickness of 0.8 mm at the most worn
part.
Replace the brake band if it is worn morethan this.
AssemblyMod. 2077/2083
Fit the brake in the reverse order to dis-
mantling.Begin by fitting the hand guard.
Lubricate the bearing pin and catch with
oil.
Place the catch in position with the
extruding part downwards.
Press away the catch by means of ascrewdriver and press down the hand
guard in the correct position.
Fit the lock-ring on the bearing pin.
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Safety equipment1
A
B
Fit the brake band (A) and place the
toggle-joint in position over its bearingpin (B).
Press together the brake spring far
enough so that the guide pin in the backof the spring housing is released.
Press down the spring and check that the
pin goes into the centre of the spring.
Press down the brake band in its rear
attachment (A).
Place the toggle-joint in position over its
bearing pin (B).
Make sure that it is correctly positioned.
Press the brake spring over the guide pin.
Push the guide sleeve in the spring and
outside of the guide pin.
Press the spring together by means of a
suitable Phillips screwdriver far enough
so that the guide pin in the back edge ofthe spring housing is released.
Press down the spring and check that the
pin goes into the centre of the spring.
Fit the chain brake on the engine.
Check that the guide pin on the chainbrake goes into the corresponding hole inthe crankcase.
L
H
Checking of the automatic function
NOTE!The engine should be switched off during this check.
Hold the saw approx. H mm over a stable object.
Release the front handle and allow the saw to turn round the back handle by virtue of
its own weight. When the guide bar point hits the object the brake should be activated.
H, cm/inch L, inch45/14 11 16
55/22 18 2265/26 24 28
80/32 30 36
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Safety equipment 1
Checking of the brake
effect
Start the engine.
Hold the handle with both hands and rev
up.
Release the chain brake by turning the
left wrist towards the hand guard withoutreleasing the grip round the front handle.
The chain should stop immediately.
Chain catcher
Replace the chain catcher if it is deformed
or cracked.
Checking of the brake
effect
Place the saw on a stable surface and
start the engine.
Hold the handle with both hands and revup.
Release the chain brake by turning theleft wrist towards the hand guard without
releasing the grip round the front handle.
The chain should stop immediately.
Chain catcher
The chain catcher has the purpose of
catching the chain if it breaks.
It is therefore important that it is not
deformed or cracked. Replace if this
should be the case.
Throttle lockDismantling
Remove the screws.
Remove the handle half, throttle controland lock.
Throttle lockDismantling
Remove the screws which hold the handle
halves together and where appropriatealso the screw which holds the spring for
the vibration damper.
Lift off the handle half and throttle controltogether with the lock.
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Fitting, mod. 2036/2040
Fit in the reverse order to dismantling.
2
1
Safety equipment1
Check that the throttle cable is correctly
fitted.
Do not lubricate!
Fitting mod. 2041/2045/2050
Check that the throttle cable is correctly
fitted.
Do not lubricate!
Fitting mod. 2054/2055
Check that the spring and throttle cableare correctly connected.
Fitting mod. 2036/2040
Replace any damaged parts and fit in the
reverse order to dismantling.
Note the following:
Make sure that the spring comes on
the correct side of the barrier in the
throttle control.
Check that the throttle cable's ball lug
sits in the recess (1).
Check that the throttle cable is flush
with the cam curve on the throttle
control (2).
Do not lubricate!
Fitting mod. 2041/2045/2050
Note the following:
Fit the throttle cable from the correct
side in the throttle control.
Check that the throttle cable is
correctly positioned so that it is not
clenched when the handle half is f itted.
Do not lubricate!
Fitting mod. 2045/2055
Note the following: The positioning of the spring in the
throttle control.
The connection of the throttle cable
from underneath to the throttle control
catch.
Do not lubricate!
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Safety equipment 1
Dismantling mod. 625/630/670
Press out the fitted pin and dismantle the
cover.
Dismantle the spring and throttle controllock.
Fitting mod. 625/630/670
Fit the throttle control lock in the reverse
order to dismantling.
Dismantling mod. 2095
Dismantle the handle half.
Dismantling mod. 625/630/670
Press out the fitted pin approx. 13-14 mm
so that the throttle control lock comes
loose.
Dismantle the covers by means of pres-sing a screwdriver into the back edge of
the covers.
If the handle is electrically heated seechap. 3 Electrical system.
Press out the sprung tubular pin which is
located behind the cover far enough sothat the spring and the throttle control
lock can be lifted off.
Fitting mod. 625/630/670
Replace damaged or worn parts and fit in
the reverse order to dismantling.
NOTE!
The sprung tubular pin should go through
the spring eyelet.
Dismantling mod. 2095
Remove the screws and lift off the handlehalf.
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1
2
Safety equipment1
Fitting mod. 2095
Replace damaged or worn parts and fit in
the reverse order to dismantling.
Fitting mod. 2095
Replace damaged or worn parts.
Fit in the reverse order to dismantling.
Pay attention to the following:
The springs straight shank should be
fitted in the throttle control lock (1).
Make sure the throttle wire housing iswell pressed down in the recess (2).
Check that the short-circuiting cable
sits in the recess so that it is notclenched when the handle half is
screwed tight.
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Contents
Dismantling 18
Replacement of return spring 19
Replacement of starter cord 20
Assembly 21
Replacement of starter pawls 22
Starter unit
2.
2
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2 Starter unit
WARNING!
When working on the starter unit wear protective glasses to avoid eye injuries in theevent that the return spring flies out.
!
Dismantling
1. Dismantle the starter from the engine
unit.
Dismantling
1. Remove all screws and lift off the
starter.
2. Release the spring tension. 2. Release the spring tension.
Pull out the starter cord approx. 30
cm. Brake the cord wheel with the
thumb and place the cord in one of therecesses on the pulley.
3. Allow the pulley to slowly rotate back-wards.
3. Allow the pulley to slowly rotate back-
wards.
NOTE!
Brake the rotation with the thumb.
WARNING!
Observe care so that the thumb is not
injured by the reinforcement ribs onthe pulley or the cord's attachment
screw.
!
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Starter unit 2
!
!
!
!
4. Remove the screw and the washer.
5. Remove the pulley and spring cass-ette, and return spring.
4. Remove the screw and washer in thecentre of the pulley.
5. Lift off the pulley carefully.
6A.Remove the screws which hold the
spring cassette and lift off.
WARNING!Wear protective glas-
ses. The return spring
can fly out and cause
injury.
WARNING!
Wear protective glas-
ses.
6B.Remove the screws which hold the
cover disc over the return spring.
Dismantle the spring by giving the
starter housing a sharp tap againstthe work bench with the spring turned
downwards.
WARNING!
Wear protective glas-
ses.
WARNING!
Wear protective glas-
ses. The return spring
can fly out and cause
injury.
Replacing return spring
Dismantle the pulley as described above.
A. Fit a new spring cassette.
Replacing return spring
Dismantle the pulley as described above.
A. Place a new spring cassette in the
starter housing and tighten the
screw(s).
6. Dismantle the cover disc and return
spring from the starter unit housing.
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2 Starter unit
! !
B. Press down a new spring in the starter
housing.
B. Return spring without cassette.
Leave the lock shackle round the
spring in position.
1. Place the spring over its seat in the
starter housing.
2. Press down the spring in the correct
position by means of the thumbs and
let the lock shackle slide over thespring.
3. Fit the cover plate off the spring.
Replacing starter cord
1. Fit and lock the cord at the pulley asper one of the methods shown in the
diagrams.
Tips!
The knot on the starter cord in the starter
handle may be difficult to untie. It is easier
if the knot is first knocked with a hammeragainst a hard surface.
2. Anchor the cord in the starter handle. 2. Enter the cord through the socket inthe starter housing and anchor it in
the starter handle by means of a knot.
Fold down the free end and pull the
knot securely into the handle.
WARNING!
Wear protective glas-ses.
WARNING!
Wear protective glas-
ses.
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Starter unit 2
1 3 r
+ 1/2 r
max
Assembly
1. Wind the cord approx. 4 turns clock-
wise round the pulley.
2. Fit the pulley.
3. Increase the spring tension.
4. Check the spring tension.
With a fully withdrawn cord it shouldbe possible to turn the pulley at least
another half turn.
Assembly
1. Wind the cord approx. 4 turns clock-
wise round the pulley.
2. Lubricate the pulleys bearing pin and
the return spring with a few drops ofmotor oil or non-freezing lubricant and
fit the pulley.
Check that the return spring grips the
pulley. The spring may require to bebent out further from the bearing pin.
3. Put the washer in place and tighten
the screw.
4. Increase the spring tension.
With a fully withdrawn cord it should
be possible to turn the pulley at least
another half turn.Tension the spring more by:
Pulling the cord approx. 30 cm and
braking the pulley with the thumb.
Lift up the cord in one of the recesses
on the pulley.
Wind the cord 1-3 turns clockwise
round the hub of the pulley.
Pull out the starter cord fully.
5. Check the spring tensions.
With a fully withdrawn cord it shouldbe possible to turn the pulley at least
another half turn.
Repeat the spring tensioning if
necessary.
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2 Starter unit
503 21 22-01
5. Assemble the starter in the reverseorder to dismantling.
Replacing starter pawls
See chapter 3 Electrical system.
6. Assemble the starter.
Pull out the starter cord a little. Put the
starter in position. Release the starter
cord and check that the pawls grip the
pulley.
Tighten the screws.
NOTE!
If the threads in the crankcase (made of
plastic) are for any reason damaged an
oversize screw (No. 503 21 22-01) is
recommended.
Replacing starter pawls
See chapter 3 Electrical system.
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Electrical system
3.
3
Contents
Checking ignition spark 24
Replacing spark plug protection 26
Dismantling 28
Starter pawls 20
Assembly 30
Electrically heated handles 31
Replacing the generator 33
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3 Electrical system
502 71 13-01
Checking ignition spark
Clean the electrodes and check the
electrode gap.
If the electrodes are worn down more
than 50% the plug should be replaced.
Check if there is a spark when starting.
Try with test plug No. 502 71 13-01 ifthere is no spark.
Checking ignition spark
Remove the plug and clean from soot by
means of steel brush.
Check the electrode gap. It should be 0.5
mm 0.7 mm (.020 .028").
Adjust the gap to correct value with side
electrode.
If the electrodes are worn down more
than 50 % the plug should be replaced.
An overlarge gap implies stress on the
ignition module and the risk of shortcircuiting.
Make sure that the stop contact is in start
position.
Earth the plug to the cylinder and pull thestart handle.
There should be a spark between the
electrodes.
If there is no spark try with the test plug
No. 502 71 13-01.
If there is a spark the fault lies in the plug.
Replace plug.
The chain saw is fitted with an electronic systemconsisting of flywheel, ignition coil, and trigger
unit. Certain saw models are fitted with a gene-rator system to heat the handles and carburettor.
The ignition system is electronic and completely
without moving parts. A defective componentcannot be repaired and must be replaced.
The ignition spark in an electronic ignition sys-tem has a very short burn time and may therefore
be experienced as weak and sometimes difficultto see during trouble shooting.
NOTE!
When testing the chain saws heating system theguide bar, chain and clutch cover must be fittedbefore the engine is started!
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25
Electrical system 3
A
B
Try with a new plug
If there is no spark disconnect the short
circuiting contact.
Replace the contact if necessary.
Try with a new plug.
If there is still no spark remove the short
circuiting cable from either the ignition
module or short circuiting contact.
If there is no spark the fault lies in the stopcontact.
Replace the contact.
Check the connections of the ignition
cable.
Still no spark?
Check the plug connection.
Pull off the rubber protection at the plug
(A) and ignition module (B) and checkthat the ignition cable is undamaged. Cut
off a piece of the cable to ensure good
contact.
Lubricate the cable ends with a littlegrease to simplify fitting and prevent
moisture from penetrating into the connec-
tions.
Lubricate the cable ends with grease.
Mod. 2077/2083
Check that the earth cable is undamaged
and that it has metallic contact with the
crankcase.
Mod. 2077/2083
Check that the earth cable between the
crankcase and stop contact is undamaged
and that it has metallic contact with the
crankcase.
Use an ohm-meter and measure theresistance in the cable between the stop
contact and connection at the crankcase.
The instrument should give a full reading
if the cable is in good condition.
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3 Electrical system
502 51 34-05
0.3 mm
502 50 06-01
Check other cables and connections. Sti ll no spark?
Check the other cables and connections
for poor contact (dirt, corrosion, cable
break and damaged insulation).
Tips!
Use an Ohm-meter to check if there is a
cable break, e.g. as a result of pinching.
Check the air gap.
Adjust the air gap.
Replacing spark plug
protection1. Take ignition cable through the spark
plug protection.
2. Make a hole in the ignition cable for
the contact spiral.
Still no spark?
Check the air gap between the flywheel
permanent magnet and ignition module.
The gap should be 0.3 mm (.012").
Use air gap measure 502 51 34-05.
Adjust the air gap to correct size.
Release screws.
Place the feeler gauge and press the
ignition module to the flywheel. Tighten the screws and check the air
gap again.
If there is still no spark the ignition system
should be replaced.
Replacing spark plug
protection1. Lubricate the ignition cable with a little
grease and take it through the plug
protection.
2. Cut off a piece of the ignition cable(approx. 5 mm, .20") and make a hole
in the cable for the contact spiral by
means of pliers No. 502 50 06-01.
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3Electrical system
504 91 06-05
3. Fit the contact spiral on the ignition
cable.
3. Fit the contact spiral on the ignition
cable and make sure that the wire isfolded along the cable.
4. Pull the contact spiral into the spark
plug protection.
NOTE!
It is important that the point of the contactspiral meets the middle of the ignition
cable to prevent sparking.
Fit a piston stop No. 504 91 06-05 alt.
502 50 33-01 in the spark plug hole.
Fit a piston stop No. 504 91 06-05 alt.502 50 33-01 in the spark plug hole.
Make sure that the piston stop is screwed
down to the bottom.
Dismantle the starter pawls.
Mod. 2054/2055
On earlier versions of these models the
starter pawls sit on a bridge which can be
lifted off when the flywheel nut is
dismantled.
Dismantling
Dismantle the plug, cylinder cover, star-
ter unit, and air bar.
Dismantle the ignition module and re-
lease the other cable connections.
Dismantling
Dismantle the plug, cylinder cover, star-
ter unit, and air conductor.
Dismantle the ignition module by remo-
ving the two screws.
Release the other cable connections and
lift off the ignition module.
Dismantle the starter pawls by releasingthe screws. Make sure that the small
washer close to the flywheel is not mislaid.
Mod. 2054/2055
On earlier versions of these models the
starter pawls sit on a bridge which can be
lifted off when the flywheel nut is
dismantled.
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3 Electrical system
502 51 49-01
502 51 94-01
Mod. 2036/2040
Dismantle the flywheel by using ahammer.
Mod. 2036/2040
Thread the nut on the shaft to protect thethreads.
Snap the springs loose and fold down thestarter pawls to leave space for the
hammer.
Grip the flywheel and lift up the engine
unit.
Give a few smart blows with the hammer
on the flywheel nut until the flywheel
releases from the shaft.
Tips!
Use a pressure piece to protect the
threads on the shaft and so that it is also
easier to use the hammer.
Remove the flywheel nut.
Pull off the flywheel.
Tips!
If the flywheel is tight give a few smart
taps with a hammer on the extractor screw.
Remove the flywheel nut by means of a
suitable socket wrench.
Pull off the flywheel by means of with-
drawing tool 502 51 49-01 which isscrewed in the hole for the starter pawls.
NOTE!
Centre the withdrawing tool over the shaftcentre. Select suitable screws and tighten
the withdrawing tool.
Tips!
The flywheel may sit very tightly on the
shaft.
To simplify dismantling give a few smarttaps with a hammer on the extractorscrew. Hold the chain saw in the air with
the handle on the withdrawing tool.
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3Electrical system
504 90 90-01
Mod. 2054/2055
Pull off the flywheel.
Mod. 2054/2055
Pull off the flywheel by means of ball
bearing puller No. 504 90 90-01.
NOTE!
The claws on the tool should be placed on
and opposite the permanent magnet on
the flywheel so that this is not damaged.
Is the flywheel stuck?
Lift up the engine unit by holding the tool
and hit the tool screw a few times with a
hammer.
Starter pawls
Check the starter pawls for wear and
damage.
Replace damaged parts.
Starter pawls
Check the starter pawls for wear and
damage.
Replace damaged parts.
For starter pawls which are mounted on aseparate bridge the entire unit must be
replaced.
Mod. 2036/2040
Press out the journals by means of a
suitable mandrel.
Replace damaged parts.
Mod. 2036/2040
Replace the starter pawls and springs in
the following way if they are housed on a
journal pressed in the flywheel.Place the flywheel on support blocks andpress out the journals by means of a
suitable mandrel.
Replace damaged parts.
Make sure that the spring is not pinchedwhen the journal is pressed into the
flywheel.
Check that the starter pawls move easily.
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3 Electrical system
0.3 mm
Assembly
Check that the keyway and key in the
crankshaft are undamaged.
Assembly
Check that the keyway and key in the
crankshaft are undamaged.
Fit a new key and make sure that it fits
correctly in the keyway.
Check that the keyway and the cast key
respectively in the flywheel are undam-aged.
Fit the flywheel.
Check that the keyway and cast key
respectively in the flywheel are undam-aged.
Fit the flywheel on the crankshaft andcheck that the key and keyway are
correctly positioned before the flywheelnut is tightened.
Tighten the nut to a torque of 2535 Nm
Fit the ignition module.
Adjust the air gap (0.3 mm, .012")Fit the other cables.
Fit the other parts in the reverse order to
dismantling.
Fit the ignition module
Adjust the air gap to the correct size(0.3 mm, .012").
See also page 26.
Fit the other cables and make sure that
they are correctly positioned in cable
grooves etc. so that they cannot be
damaged.
Fit the other parts in the reverse order to
dismantling.
When fitting the starter pawls check the
following:
Washer between flywheel and starter
pawls.
The spring is not clenched.
The starter pawls move freely.
Use Locktite on the screw.
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3
1
2
Electrical system
A
B
A
Electrically heated
handles
Certain of our chain saws are fitted with
electric heating of both the the front and
rear handles.
Trouble shooting in heating
system
Use a universal tool set for resistance
measuring during trouble shooting.
Mod. 625/630/670
Checking rear handle element
Dismantle the cover plate and screw on
each side of the handle.
Fold out the heater element from thehandle to check.
Electrically heated
handles
The requisite output is generated by a
generator placed behind the flywheel.
The electrical system is maintenance free
and is controlled by means of a switch on
the left-hand side of the chain saw.The generators max. output is 80 W.
Trouble shooting in the heating
system
Measure the resistance (Ohm) in the
different heating coils.
Use a universal instrument set for
resistance measuring.
Checking the switch
Dismantle the switch. Bend with a small
screwdriver.
Connect the measuring instrumentbetween the two connections on the
switch (1) and (2).
When the heat is switched on the indicator
should give a reading, and vice versa
when switched off.
Mod. 625/630/670
Checking of rear handle
element
In order to dismantle the handle element(for checking or replacement) the plastic
cover plates over the screws must beremoved.
Carefully drill a small hole in the plate (so
as not to damage the underlying screw
heads) on each side of the handle and
then bend off with a pointed object.
Fold out both heater elements from thehandle so that they become accessible
for checking.
The most common fault is oxidation at the
cable connections (A) and in the rear
socket-contact (B).
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3 Electrical system
1
2
4
3
1
2
3
4
5
6
Clean and measure bothhandle inserts between points 2 and 3. The switch should bein the switched off position. Correct measurement value: 1.4 - 1.8 Ohm.
If the values measured differ from the recommended values measure each insert
separately.
Connect the instrument between points 4 and 2, and 4 and 3.
Correct measurement value for one handle insert: 0.7 - 0.9 Ohm.
Checking of the front handle element
Connect the measuring instrument between the points 1 and 3. The heater switchshould be switched off. Correct measurement value: 4 Ohm 0.5 Ohm.
If the heater element is defective the complete front handle must be replaced.
Checking of all heater coils
The two rear handle inserts and front handle are checked as follows:
Connect the measuring instrument between points 1 and 2. The switch should be
switched off.
Correct measurement value: 5.1 - 5. 7 Ohm.
Deviations in the values can be the result of defective components, oxidation, flash-
over or a break in the circuit.
Checking of the generator
The voltage is measured when the chain saw is run at approx. 10.000 rpm. Measure
between point 1 and the crankcase. The switch should be switched on and all heater
coils connected. Correct measurement value: approx. 20 volts at 10.000 rpm.
Possible faults:
Break in generators windings. Weak magnetisation in the flywheel.
Cable break.
WARNING!
The chain, guide bar and clutch cover must be fitted before the chain saw is started.
Mod. 2054/2055
Checking of the front handle element
Connect the measuring instrument between the points 2 and 3. The heater switch
should be switched off. Correct measurement value: 5 Ohm 0.5 Ohm.
The complete front handle must be replaced if the heater element is defective.Checking of the carburettor heating
Connect the measuring instrument between the points 4 and 5. The heater switch
should be switched off. Correct measurement value: 5 Ohm 0.5 Ohm.
Checking of the rear handle element
The rear handle insert is checked as follows:
Connect the measuring instrument between points 2 and 6 (earth). The switch should
be switched off.
Correct measurement value: 0 Ohm 0.1 Ohm.
Deviations in the value can be the result of defective components, oxidation, flash-over
or a break in the circuit.
Checking of all heater coils incl. the carburettor element
Connect the measuring instrument between point 1 and earth.
Correct measurement value with switch in position handle heating: 5 Ohm 0.5 Ohm.Correct measurement value with switch in position distributor heating: 5 Ohm 0.5
Ohm.
Checking of the generator
The voltage is measured when the chain saw is run at approx. 10.000 rpm. Measure
between point 1 and the crankcase. The switch should be switched on and all heater
coils connected. Correct measurement value: approx. 20 volts at 10.000 rpm.
Possible faults:
Break in generators windings. Weak magnetisation in the flywheel.
Cable break.
WARNING!
The chain, guide bar and clutch cover must be fitted before the chain saw is started.
!
!
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33
3Electrical system
502 71 23-01
Replacing the generator
Replace the generator if it does not prov-
ide sufficient voltage.
Place the new generator in position and
centre it before tightening the screws.
Replacing the generator
The generator must be replaced if the
voltage proves to be insufficient when
checked.
The generator is placed behind the
flywheel.
Remove the screws and lift off the gene-rator.
Place the new generator in position
against the crankcase. Check that thecable is not clenched.
Use mandrel No. 502 71 23-01 to centre
the generator to the crankshaft.
Tighten the screws.
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4
4.Fuel system
Contents
Air filter 36
Centrifugal cleaning (Turbo) 37
Fuel filter 37
Carburettor 38
Carburettor design 44
Carburettor setting 49
Fuel tank vent 51
Trouble shooting schedule 53
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36
4 Fuel system
In addition to the fuel tank and carburettor, the
fuel system also includes the air filter, fuel filterand tank vent.
All these components interact to ensure that the
engine will have the optimum mixture of fuel andair to make it as efficient as possible. Very smalldeviations in the carburettor setting, or fouling ofthe air filter, have a great effect on the running
and efficiency of the engine.
There are different makes of carburettors on our
different models, but the function and repairtechniques are basically the same.
Air filter
Dismantle the cylinder cover and air filter
cover so that the filter is accessible.
The material in the air filter can be either
felt or fine mesh nylon.
Both types are cleaned with lukewarm
soapy water.A damaged filter should be replaced witha new one.
Dismantle the air filter from either the
carburettor or the holder.Clean also the holder/cover before the
cleaned filter is refitted.
Air filter
Dismantle the cylinder cover and air filter
cover so that the filter is accessible.
The material in the air filter can be either
felt or fine mesh nylon.
Both types are cleaned with lukewarm
soapy water.A damaged filter should be replaced witha new one.
WARNING!
Do not clean the filter in petrol. Health
hazard!
NOTE!
The filter must be dry when it is refitted.
!
The air filter can be fitted in different
ways.
With screws directly on the carburettor
or in a special holder.
Snap fixture in a special holder.
In the latter case a screwdriver can beplaced between the pins on the filter
and holder to separate both parts.
Clean also the holder/cover before
the cleaned filter is refitted.
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37
4
502 50 83-01
Fuel system
Centrifugal cleaning (Turbo)
By means of utilising the centrifugal power during the cleaning of the induction air to
the carburettor the air filter is guarantied much longer cleaning intervals.
By means of the centrifugal power the larger impurities are sorted out since they are
thrown out to the periphery of the air shell and out past the cylinder.
The air to the carburettor is captured by the turbo nozzle and the finer impurities are
effectively absorbed in the air filter.
In order for centrifugal cleaning to be as effective as possible it is important that:
1. The turbo nozzle is clean from deposits.
2. The connection of the nozzle to the carburettor chamber is tight.
3. The nozzles guide pins are not broken. The pins are important for the correct
positioning of the nozzle in the air flow.
4. The fan shell and air conductor are cleaned.
The turbo nozzle is accessible for cleaning or replacement after the starter and air
conductor have been dismantled.
Fuel filter
The fuel filter can be taken out throughthe tanks filler hole.
Clean the filter externally if it is not too
severely fouled.Replace the filter if necessary.
Fuel filter
On the fuel pipe in the tank there is a fuel
filter. This is accessible through the filler
hole. Pull out the filter with your fingers orby means of tool 502 50 83-01.
Remove the tank cap completely.
If the filter is not too severely fouled it can
be cleaned externally by means of abrush.
Otherwise it must be replaced.
Check the fuel pipe for cracking andleakage.
NOTE!
Make sure that the filters connecting
collar is pressed as far as possible in thefuel pipe.
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38
4 Fuel system
CarburettorDismantling, all models
Dismantle the cylinder cover and car-
burettor cover and blow clean the car-
burettor chamber with compressed air.
Dismantling mod. 2036/2040
Dismantle the carburettor.
Fitting mod. 2036/2040
Enter the throttle wire through the hole
and the guide in the air filter holder.
Connect the fuel pipe and throttle wire.
Position the screws.Connect the choke lever.
CarburettorDismantling, all models
Dismantle the cylinder cover and
carburettor cover.
Close the choke valve to prevent dirt
entering the engine.
Blow clean the carburettor chamberwith compressed air.
Dismantling mod. 2036/2040
Dismantle the air filter and air filter holder,
fuel pipe, throttle wire and choke lever.
Lift off the carburettor.
Fitting mod. 2036/2040
Enter the throttle wire through the hole
and the guide in the air filter holder as
shown in the diagram.
NOTE!
Check that the throttle wire is put in the
holder from the correct side.
Connect the fuel pipe to the carburettor.
Connect the throttle wire to the lever.Push the screws (the right-hand first)
through the air filter holder and carburettor
body.
Connect the choke lever by pressing inthe pin in the lever with a screwdriver.
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39
4Fuel system
Place the gasket on the carburettor and
tighten the screws.
Connect the screwdriver guide.
Fit the air filter.
Dismantling mod. 2041/2045/
2050
Fold back the handlebar and remove the
air filter.
Dismantle the screws which hold the sup-
port over the stop switch respectivelyfilter holder.
Lift off the air filter holder.
Disconnect the throttle wire and fuel pipe.
Fitting mod. 2041/2045/2050
Connect the fuel pipe and throttle wire.
Tips!
Place the carburettor gasket, preferably
with gasket paste, on the carburettor.
Position the screws through the holes
approx. 5 mm to centre the gasket.
Tighten the screws. Begin with the right-
hand side.
Connect the screwdriver guide on the
carburettors adjusting screws.
Fit the air filter.
Dismantling mod. 2041/2045/
2050
Dismantle the screws and fold away the
handlebar to simplify dismantling and
fitting of the carburettor.
Remove the air filter by prizing off with ascrewdriver.
Fold away the pipe for the tank vent.
Dismantle the screws which hold the sup-port over the stop switch respectively
filter holder.
Fold the screwdriver support for the
carburettors adjusting screws to one sideand lift off the air filter holder.
Disconnect the throttle wire and fuel pipe.
Fitting mod. 2041/2045/2050
Connect the fuel pipe and throttle wire.
NOTE!
The throttle wire should be drawn between
the carburettor body and the lever for the
idling screw.
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40
4 Fuel system
Fix the carburettor gasket on the car-
burettor.
Place the filter holder against the car-burettor and push in the screws so that
they stick out approx. 3 mm to simplify
centring to the spacing piece.
Tighten the screws and make sure not to
forget the earth cable.
Fit the air filter and handlebar, including
the pipe for the tank vent.
Dismantling mod. 2054/2055
Lift up the nonreturn valve.
Dismantle the carburettor screws.
Fit the carburettor gasket on the car-
burettor with gasket paste. Make sure
that it is turned the right way round so that
the impulse channel is not blocked.
Place the filter holder against the car-
burettor and fold in the screwdriver guide
over the adjusting screws.
Place the carburettor screws so that theystick out approx. 3 mm and centre the
carburettor to the spacing piece.
NOTE!
Check that the choke lever goes into the
groove on the lever.
Tighten the screws for the carburettor
and the support over the the stop switch.
NOTE!
Do not forget the earth cable at the stop
switch.Fit the air filter and handlebar, including
the pipe for the tank vent.
Dismantling mod. 2045/2055
Lift up the tank vents nonreturn valve to
improve accessibility.
Place a screwdriver, or the like, to angle
up the carburettor so that it is easier to get
at the screws.
Unscrew the carburettor screws.
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4
1
23
4
5
6
1
2
3
502 50 87-01
4
Fuel system
Lift up the carburettor and dismantle:
1. The screwdriver guide for the carbu-
rettors adjusting screws.
2. The ventilation pipe from the nipple
on the fuel tank.
3. The carburettor screws.
4. The air filter connection.
5. The choke lever.
6. The throttle wire.
Dismantle the fuel pipe and impulse pipe.
Lift off the carburettor.
Fitting mod. 2054/2055
Fit the carburettor in the reverse order todismantling.
Make sure the throttle wire is connectedfrom the correct side.
Dismantling mod. 625/620/670
Dismantle the air filter and following parts:1. The throttle controls push rod.
2. The impulse pipe.
3. The fuel pipe.
4. The choke lever.
Lift up the carburettor and dismantle:
1. The screwdriver guide for the carbu-
rettors adjusting screws.
2. The ventilation pipe from the nipple
on the fuel tank.
3. The carburettor screws.
4. The air filter connection.
5. The choke lever.
6. The throttle wire.
Turn the carburettor and dismantle the
fuel pipe and impulse pipe.
The fuel pipe is provided with a wire spiralto prevent it being bent and restricting the
fuel flow.
Tips!
Turn the spring clockwise so that it iseasier to move along the pipe.
Use a screwdriver to push the fuel pipe
away from the nipple.
Fitting mod. 2054/2055
Fit the carburettor in the reverse order to
dismantling.
Screw in the left-hand screw first. Usescrewdriver No. 502 50 87-01.
Angle up the carburettor with a screwdriver
and screw tight the right-hand screw.
NOTE!
The throttle wire should be connected
to the lever from the inside and out.Otherwise the choke lever will not
function satisfactorily.
The pipe for the tank vent should lie
underthe fuel pipe.
Dismantling mod. 625/630/670
Dismantle the air filter and following parts:1. The throttle controls push rod (use a
screwdriver).
2. The impulse pipe.
3. The fuel pipe.
4. The choke lever (use a screwdriver).
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42
4
502 50 87-01
502 51 67-01
1
2
3
4
A
Fuel system
Unscrew the carburettor screws and liftup the carburettor.
Fitting mod. 625/630/670
Fit the carburettor in the reverse order to
dismantling.
Place the air filter connection and car-burettor screws on the carburettor.
Fit the screwdriver guide on the adjustingscrews.
Push in the tap on the air filter connection
in the vibration damper.
Press down the carburettor and connect
the screwdriver guide against the crank-
case.
Screw tight the carburettor screws.Use screwdriver No. 502 50 87-01 whichpermits a slight angular adjustment.
Dismantling mod. 2077/2083
Dismantle the air filter holder.
Unscrew the carburettor screws and liftup the carburettor.
NOTE!
The screw (A) which holds the vibration
damper should not be dismantled.
Fitting mod. 625/630/670
Fit the carburettor in the reverse order to
dismantling.
Place the air filter connection and car-burettor screws on the carburettor.
Fit the screwdriver guide on the adjustingscrews.
Push in the tap on the air filter connection
in the vibration damper.
Press down the carburettor and connect
the screwdriver guide to the crankcase.
Screw tight the carburettor screws.
Use screwdriver No. 502 50 87-01 whichpermits a slight angular adjustment.
Dismantling mod. 2077/2083
Remove the impulse pipe (1) and chokelever (2).
Lift up the throttle push rod (3) and re-
lease the carburettor screws (4).
Use screwdriver No. 502 51 67-01 (Torx).
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43
4
502 51 67-01
1
23
4
5
6
7
1
23
A
Fuel system
Lift up the carburettor and remove the airfilter holder, throttle push rod and fuel
pipe.
Fitting mod. 2077/2083
Fit the carburettor in the reverse order to
dismantling.
Dismantling mod. 2095
Dismantle the covers so that the car-
burettor becomes accessible.
Unscrew the carburettor screws and pull
them out approx. 15 mm.Tilt and push the carburettor sideways to
the right until the screwdriver guide
releases from the carburettors adjusting
screws.
Lift up the carburettor and remove the airfilter holder, throttle push rod, and fuel
pipe.
Fitting mod. 2077/2083
Fit the carburettor in the following order:
1. Connect the fuel pipe.
2. Connect the throttle push rod.
3. Connect the impulse pipe.
4. Place the air filter holder in positionand push the carburettor screws
completely in the carburettor so that
they are visible and thereby simplifing
centring to the suction pipe.
5. Press down the throttle push rods
guide in the crankcase.
6. Tighten the carburettor screws.
7. Connect the choke lever.
8. Fit the air filter.
Unscrew the carburettor screws and pull
them out approx. 15 mm.Tilt and push the carburettor sideways to
the right until the screwdriver guide (A)releases from the carburettors adjusting
screws.
Dismantling mod. 2095
Dismantle the carburettor cover, air filter
cover and cylinder cover, and then:
1. The impulse pipe.2. Fuel pipe.
3. Choke lever.
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4 Fuel system
Lift up the carburettor and release the
throttle wire.
Fitting mod. 2095
Fit the carburettor in the reverse order to
dismantling.
Design of the
carburettor
The carburettor can be divided into three
different functional sections: the mete-
ring section, mixing section, and pumping
section.
The metering section
The nozzles and control function for the
fuel are placed here.
The mixing section
The fuel and air are mixed here.
Lift up the carburettor and give full throttle
by turning the throttle shaft. Lift up the
throttle wire from the guide and releasethe tank vent pipe.
Fitting mod. 2095
Fit the carburettor in the reverse order to
dismantling.
Pay attention to the following:
Do not forget the brass ring in the
suction pipe. Turn it the right wayround!
Observe care when screwing in the
carburettor screws to avoid cross
threading.
Design of the
carburettor
The carburettor can be divided into three
different functional sections: the metering
section, mixing section, and pumping
section.
The metering section
The nozzles and control function for the
fuel are placed here.
The needle valve and metering diaphragm
are vital parts for the functioning of the
carburettor.
The mixing section
The fuel and air are mixed in this part ofcarburettor to the correct proportions.
The choke and throttle valves are placed
here.
The main jet nozzle is located in themiddle of the Venturi (the narrowest point
on the inlet).
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4
502 50 38-01
Fuel system
The pumping section
This pumps fuel from the tank to thecarburettor.
Disassembling the carburettor
Remove the metering diaphragm and
check for damage.
Replace if necessary.
In the event of leakage - dismantle the
needle valve.
Pressure test the metering section.
The pumping section
The pump diaphragm which pumps fuelfrom the tank to the carburettors mete-
ring section is placed here.
The diaphragm is activated by the
pressure variations in the enginescrankcase via an impulse channel.
If the channel is blocked, e.g. by greaseor an incorrectly positioned gasket, the
pump will not function and it will not be
possible to start the engine.
Disassembly of the carburettor
Remove the 4 screws which hold the
metering diaphragm cover and lift off the
cover.
Carefully remove the metering diaphragm
and gasket.Check the diaphragm for holes and wear
on the pin.
Replace the diaphragm if necessary.
Connect pressure tester 502 50 38-01 to
the fuel pipe nipple.
Submerge the carburettor in a basin
containing petrol in order to more easilydiscover leakage.
Pressure test with 50 kPa.
No leakage is permissible.
If leakage occurs dismantle the needle
valve.Unscrew the screw and lift off the lever,
shaft, needle valve and spring.
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4 Fuel system
Check the needle valve and lever for
wear.
Replace damaged parts with new ones.
Remove the pump diaphragm.
Check the diaphragm for wear.
Remove the fuel filter.
Unscrew both nozzle needles.
Check the needle valve for wear on the
point and in the groove for the lever.
Check the lever for wear on the groove for
the lever and on the contact point to themetering diaphragm.
Replace damaged parts with new ones.
Remove the screw which holds the cover
over the pump diaphragm.
Lift off the cover, gasket and diaphragm.
Check the diaphragm for damage on the
valve tongues. Hold it up to a light to
check for holes in the material.
Carefully remove the fuel filter, e.g. by
using a needle.
Unscrew the nozzle needles.
NOTE!
Notice how the needles are placed (e.g.
the H-needle is slightly shorter than the L-
needle.
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4
1
2
Fuel system
Dismantle the welch plug (1) and main jet
nozzle (2).
Check the valve and valve shafts for
wear.
Replace if necessary.
Assembly of the carburettor
Blow clean the carburetter housing.
Fit a new welch plug.
Fit a new main jet nozzle.
Drill a small hole in the welch plug (1) and
carefully break it loose with a pointed
object.
Press out the main jet nozzle (2) with asuitable mandrel.
Dismantle the valve and valve shafts. If
these parts are worn the engine will not
idle correctly.
Always replace the valve and valve shafts
at the same time.
Assembly of the carburettor
Blow clean all channels in the carbu-
rettor housing.
Fit a new welch plug.Use a suitable mandrel to ensure
complete tightness.
Press in a new main jet nozzle. Itshould lie level with the carburettor
housing.
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502 50 38-01
4 Fuel system
Fit the valve and valve shafts.
NOTE!
Use Locktite on the valve screws.
Fit the pump section parts in the reverse
order to dismantling.
Fit the different parts in the metering
section in the reverse order to dismantling.
Check that the carburettor is tight.
No leakage is permissible at 50 kPapressure.
Fit the valve and valve shafts.
NOTE!
Check that the valve and valve shafts are
turned the right way round and that they
seal completely tight in closed position.
Use Locktite on the valve screws.
Tips!
Any number designations on the valve
should be able to be read from outside.
Replace the fuel filter if it is damaged or
cannot be cleaned.
Place the pump diaphragm closest to the
carburettor housing, followed by thegasket and cover.
Fit the different parts in the metering
section in the reverse order to dismantling.
NOTE!The H-needle is slightly shorterthan the
L-needle.
Check that the lever is level:
With the carburettor housing
(Tillotson).
With the cast heads (Walbro, Zama).
Too high setting = too much fuel.
Too low setting = too little fuel,
Connect pressure tester No.
502 50 38-01 to the fuel intake in the
carburettor.
Pump up to 50 kPa pressure.
Submerge the carburettor in a basin
containing petrol to more easily discoverleakage.
No leakage is permissible.
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4
11 1/411 1/4
Fuel system
!
Fit the metering diaphragm. Place the gasket on the carburettor
housing followed by the metering dia-phragm.
Check that the air hole in the cover is
open and screw tight the cover.
Carburettor setting
WARNING!
When test running the engine in connection with adjusting the carburettor, the
clutch and clutch cover must without exception be fitted.
Otherwise there is a risk that the clutch can come loose and cause seriouspersonal injury.
Function
The purpose of the carburettor is to deliver a combustible mixture of air and fuel to the
cylinder.
The quantityof this mixture is regulated with the throttle control.
The composition of the mixtureof petrol and air is regulated by means of the adjustable
nozzles H and L.
In order for the engine to provide maximum power at different speeds, run smoothly at
idling speed and respond quickly to the throttle, it is necessary for the nozzles to be
correctly adjusted.
The adjustment of the carburettor can vary somewhat depending on humidity, tempera-
ture and air pressure.
L = Low speed nozzle
H = High speed nozzle
T = Adjuster screw for idling speed
With the L- and H-nozzles the required fuel quantity is adjusted to the air flow whichthe opening of the throttle control permits. If they are screwed clockwise the air/fuel
mixture becomes lean (less fuel), and if they are screwed anti-clockwise the air/fuelmixture will be rich (more fuel). A leanmixture gives higherspeed and a richmixture
gives lowerspeed.
The T-screw regulates the throttle controls position at idling speed. If the T-screw
is screwed clockwise a higher idling speed is obtained, and if it is screwed anti-
clockwise a lower idling speed is obtained.
Basic setting
The carburettor is given a basic setting during test running at the factory. The basic
setting is richer than the optimum setting (the overspeed lies at 600-800 rpm below
the recommended max. overspeed) and should be retained during the first hours the
engine is in operation. After this the carburettor should be fine adjusted. The basic
setting can vary between:
H = 1 to 1 1/4 turn.
L = 1 to 1 1/4 turn.
Fine adjustment
When the engine is run in the carburettor should be adjusted.
During all adjustments the air filter should be clean and the cylinder cover fitted.
The L-nozzle is adjusted first, followed by the H-nozzle and finally the idling screw T.
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50
4 Fuel system
The following rpm are recommended:
Max overspeed
Model During running in After running in*
625 11.800 11.900 12.500
630 11.700 11.900 13.000
670 12.700 12.900 13.5002036 12.200 12.400 13.000
2040 12.200 12.400 13.000
2041 11.700 11.900 12.500
2045 11.700 11.900 12.500
2050 11.700 11.900 12.500
2054 12.200 12.400 13.000
2055 13.700 13.900 14.500
2077** 12.700 12.900 13.500
2083 12.700 12.900 13.500
2095 12.200 12.400 13.000
* The speed refers to standard bar lengths and Jonsered two-
stroke oil.
When using a longer bar or another quality of two-stroke oil
use the recommended running in speed.
** Digital ignition system with speed limiter at 13.500 rpm.
Idling speed = 2.500 rpm.
NOTE!
The maximum recommended rpm must not be exceeded.
Check the rpm with tachometer 502 71 14-01.
Carefully screw in (clockwise) the L and H nozzles to the
bottom and then unscrew (anti-clockwise) the nozzles one
turn. The carburettor now has the setting H = 1 and L = 1.
Use special screw driver 501 60 02-02.
Start the engine and run warm for 10 minutes.
NOTE!
If the cutting equipment rotates at idling speed the T-screw
should be turned anti-clockwise until it stops.
Low-speed nozzle L
Set the highest idling speed by slowly screwing the low-speed
nozzle clockwise respectively anti-clockwise. When the highest
revs have been found the L-nozzle is screwed anti-clockwise 1/
4 turn.
High-speed nozzle H
The high-speed nozzle H influences the power output of the
engine and the speed. A too lean set high-speed nozzle H (the
H-nozzle screwed in too far) gives too little fuel to the engine and
will result in damage to the engine.
Run the engine at full throttle for about 10 seconds. The H-
nozzle is correctly adjusted when the engine putters slightly.
If a lot of smoke comes from silencer at the same time as the
engine putters a lot the setting is too rich. Turn the H-nozzle
clockwise until the setting sounds right.
NOTE!
For optimum setting a tachometer should be used.
The recommended maximum overspeed should not beexceeded.
Idling screw T
Let the engine idle for about 30 seconds or until the speed has
stabilised. Adjust the set screw for the idling speed until theengine runs at idling speed without stopping.
Turn the screw clockwise if the engine stops.
Turn the screw anti-clockwise to reduce the speed.
Correctly adjusted carburettor
A correctly adjusted carburettor implies that the engine
accelerates without hesitation and does not putter at full throttle.
A too lean set L-nozzle implies that the engine can be difficult
to start and gives poor acceleration.
A too lean set H-nozzle gives a lower output, poor accelera-tion and/or engine damage.
An over rich setting of both the L- and H-nozzles gives
acceleration problems or an excessively low working speed.
502 71 14-01
501 60 02-02
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4
AB C
Fuel system
Fuel tank vent
The tank air vent has a great effect on the function of the carburettor. If it is not func-
tioning either an overpressure or underpressure can develop in the tank.
Overpressure results in flooding the carburettor.
Underpressure results in diminished or no fuel flow to the carburettor.
The purpose of the tank air vent is therefore to maintain atmospheric pressure in the
tank during all operating conditions.A = Expansion volume
B = Non return valve
C = Filter
Function check
Empty the fuel tank and tighten the tank cap.
Connect the pressure gauge to the fuel pipe (the carburettor may have to be dismantled
to gain access to the pipe).
Overpressure
Pump up a pressure of 50 kPa (0.5 kp/cm2).
The pressure should fall to 20 kPa (0.2 kp/cm2) within 60 seconds.
Underpressure
Reduce the pressure to 50 kPa (0.5 kp/cm2).
The pressure should increase to 20 kPa (0.2 kp/cm2) within 30 seconds.
Model 2036/2040
Dismantle the carburettor and spacing
piece in order to access the valve for
cleaning.
Model 2041/2045/2050
Clean the filter at the pipe end at regularintervals.
Model 2036/2040
The tank air vent here is a sintered bronze
filter which is pressed secure in the fuel
tank.It is accessible for external cleaning when
the carburettor and spacing piece are
dismantled.
See chapter 8 Crankshaft and crankcasefor information on replacing.
Model 2041/2045/2050
The tank air vent consists of a pipe. Oneend is connected to the top of the tank in
the carburettor chamber.
The other end opens into the area between
the handlebar and the clutch cover.
There is a sintered bronze filter in the pipe
which must be cleaned from dirt at regular
intervals.
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4
1
A
B
Fuel system
Model 625/630/670
The valve is pressed in the tank on the
right-hand side immediately behind the
handlebar attachment.
NOTE!
The valve is notscrewed secure.
The valve can be replaced as follows:
1. Remove the tank cover completely.
2. Put a pair of flat pliers through the
tank cover hole.
3. Grip the valve and break off the pipe.
4. Press out the valve with a suitable
mandrel.
Press in a new valve with a suitable
mandrel.
Other models
The tank air vent consists of a nonreturn valve (A) and a sintered filter (B).
The nonreturn valve is open in both directions but to a different degree. It is therefore
important that it is positioned correctly. The short part 1) should be connected to thetank.
Pressure test the valve in both directions.
If there is overpressure in the fuel tank the valve opens quickly at approx. 20 kPa
(0.2 kPa/cm2) and is completely open at 30 kPa (0.3 kp/cm2).
If there is underpressure in the tank the valve opens immediately.
Replace the valve if it does not function as intended.
Model 625/630/670
The valve is pressed in the tank on the
right-hand side immediately behind the
handlebar attachment.
NOTE!
The valve is notscrewed secure.
The valve can be replaced as follows:
1. Remove the tank cover completely.
2. Put a pair of flat pliers through the
tank cover hole.
3. Grip the valve and break off the pipe.
4. Press out the valve with a suitable
mandrel.
Press in a new valve with a suitable
mandrel.
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53
4Fuel system
Trouble-shooting chart
Start 1
23
4
5
6
7
8
9
1011121314
15161718192021222324252
62728293031323334353637
383940
A
B
C
Idle
D
E
F
G
H
J
Acce
lerat
ion,
dece
lera
tion
K
L
M
Highspee
d
N
O
P
41
Start
A.Hardstarting
B.Fueldrippingfrom
carburettor
C.Floodswhen
engineisnot
running
Idle(Low
spee
d)
D.Willnotidle
E.Richidle
F.IdleswithL-needle
closed
G.Irregularidle
H."L"-needleneeds
frequentadjustment
J.Loadsupwhile
idling
Acce
lera
tionan
d
dece
lera
tion
K.Willnotaccelerate
L.Enginestopswhen
closingthrottle
M.Over-richaccelera-
tion
Highspee
d
N.Willnotrunatfull
throttle
O.Lowpower
P.Willnot4cycle
Adjus
tmen
ts
1.Lowspeedneedle(L)
2.Highspeedneedle(H)
Fue
ls
ys
tem
3.Pluggedtankvent
4.Pluggedtankfilter
5.Res
trictedfuelline
6.Dirt
infuelpassage
7.Loo
se,damagedfuelline
8.Lea
kinpulsesystem
9.Res
trictedpulsechannel
10.Loo
sepumpcoverscrews
11.Defectivepumpdiaphragm
Airsys
tem
12.Pluggedairfilter
13.De
fectivemanifoldgasket
14.Lo
osecarburettormountingscrews
15.Wornthrottleassembly
16.Incorrectthrottleassembly
17.Lo
osethrottlevalvescrew
18.Th
rottleshafttootight
19.Be
ntthrottlelinkage
20.De
fectivethrottlespring
21.Be
ntthrottlestoplever
22.Ch
okenotfunctioningproperly
23.Wornchokeshaft
24.Wornchokevalve
25.Wornthrottlevalve
Me
teringsys
tem
26.Wornlever
27.Settoohigh
28.Settoolow
29.Notfree
30.Distorted
31.Improperlyinstalled
32.Leaking(air/fuel)
33.Wornbutton
34.Improperassembly
35.Defectivegasket
36.Loosediaphragmrivet
37.Holeindiaphragm
38.Loosecoverscrews
39.Foreignmatter
40.Binding
41.Wornneedlebodyortip
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5
5.Centrifugal clutch
Contents
Mod. 2036/2040
Dismantling 56
Fitting 57
Mod. 2041/2045/2050
Dismantling 57
Fitting 58
Mod. 2054/2055
Dismantling 59
Fitting 59
Mod. 625
Dismantling 60
Fitting 61
Mod. 630/670, 2077, 2095
Dismantling 61
Fitting 62
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5
502 50 33-01 530 03 11-12
min. 1 mm
Centrifugal clutch
The centrifugal clutch has the purpose of transferringthe power between the engine and the cutting equipment.
As the name implies it works according to the centrifu-gal principle.
This principle implies that the clutchs friction shoes areslung outwards towards the clutch drum at a specific
engine speed. When the friction against the drumbecomes sufficient it is driven round at the same speedas the engine.
WARNING!
Never start or test run the engine if the clutchcover is removed. The clutch can come looseand cause personal injury.
There is a certain degree of slip between theclutch and the clutch drum during acceleration,
but also in the reverse case if the cuttingequipment should stick. This avoids irregularload alternations on the crankshaft.
The engagement speed is carefully tested so thatthe engine can run at idling speed without the
cutting equipment rotating.
!
Dismantling mod. 2036/2040
Dismantle the clutch from the crankshaft.
Press the clutch apart with your thumbs
Check the wear on the clutch.
The clutch shoes must have a thickness
of at least 1 mm at the most worn point.
Dismantling mod. 2036/2040
Remove the clutch cover, chain and bar.
Fit piston stop No. 502 50 33-01 in the
plug hole.
Use tool 530 03 11-12 and unscrew the
clutch from the crankshaft.
Press out the clutch centre from the backof the clutch with your thumbs.
Clean and inspect the different parts for
wear.
The clutch shoes must have a thickness
of at least 1 mm at the most worn point.
If they are more worn than this the
complete clutch must be replaced.
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5
502 50 33-01
Centrifugal clutch
Inspect the wear on the clutch drum.
The inner diameter must not exceed 64.4
mm.
Fitting mod. 2036/2040
Fit the clutch and lubricate the clutch
drums needle bearing with grease.
Dismantling
mod. 2041/2045/2050
Dismantle the clutch from the crankshaft.
Take the clutch apart.
Lift off the clutch drum and inspect it for
wear on the drive wheel and friction sur-face on the clutch shoes.
The drums inner diameter must not
exceed 64.4 mm.
Otherwise replace the clutch drum.
Fitting mod. 2036/2040
First place the clutch spring in position in
one clutch shoe. The springs coupling
point should be in the middle of the shoe.
Place the other clutch shoe on the hub
and fit the spring by using a screwdriver.Lubricate the clutch drums needle bearing
with grease and fit the clutch on the
crankshaft.
NOTE!
Do not overload the spring.
Dismantling
mod. 2041/2045/2050
Replace the plug with piston stop No.
502 50 33-01 and dismantle the clutchfrom the crankshaft.
Take the clutch apart by pressing theclutch shoes backwards with your thumbs.
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58
5
m
in.1mm
Centrifugal clutch
The clutch shoes must have a thickness
of at least 1 mm.
Check the spokes of the clutch centre
and the shoe guide grooves for wear.
Inspect the clutch drum for wear.
The inner diameter must not exceed 64.5
mm.
Fitting mod. 2041/2045/2050
The springs coupling point should lieopposite the groove for the centres spo-
kes.
Check that the shoes have a thickness ofat least 1 mm at the most worn point.
All three shoes must be replaced at the
same time to avoid imbalance.
Check that the clutch centres spokes are
not severely worn or show signs ofcracking, and that the guide groove in the
clutch shoes is not worn. All the shoes
and the clutch centre must be replaced at
the same time.
Lift off the clutch drum and inspect it forwear on the drive wheel and the clutch
shoe friction surfaces.
The inner diameter of the drum must notexceed 64.5 mm.
Otherwise replace the clutch drum.
Fitting mod. 2041/2045/2050
When assembling the clutch the spring isfirst placed in position in one clutch shoe
so that the springs coupling point comes
opposite the groove for the centres spo-k